Fluid-operable control mechanism for variable delivery fluid pumps



1952 w. R. TUCKER 2,614,500

FLUID-OPERABLE CONTROL MECHANISM FOR v VARIABLE DELIVERY FLUID PUMPS Filed Aug. 25. 1948 3 Sheets-Sheet l T/l Zzrren lZ'Tuo/k'ez' warne'd oct. 21, 1952 TUCKER I 2,614,500

.FLUID-OPERABLE CONTROL MECHANISM FOR VARIABLE DELIVERY FLUID PUMPS Filed Aug. 25, 1948 .3 Sheets-Sheet 2 55 34 58 56 f 29 4 30 33 5; Y 54' v as r 55 .25 as Q 34 a2 /4= v I i F]: G. 2.

36 2a 2 gz F1 G. 5. v 3 WQZ'ZKIZ'R Zbck i' Oct. 21, 1952 w, TUCKER 2,614,500

FLUID-OPERABLE CONTROL MECHANISM FOR VARIABLE DELIVERY FLUID PU Fil ed Aug. 25, 1948 MP5 3 Sheets-Sheet 5 FIG. 5.

Qwue/wwv T l zzrren Tucker pre-determined pressure, the flow-control member generally comprising what is known as a shift ring whose relative positions with respect to a driven rotor determines the operability of a plurality of radially disposed fluid-displacing plungers or pistons. Pumps of this general nature are used extensively in connection, with relatively high-pressure hydraulic systems, such as are used to operate hydraulic presses and the like.

In the drawings, the numeral it generally represents a radial piston-type'pump provided with an outer casing ll formed internally with a pair of diametrically opposed bosses l2 having flat surfaces i3 for reciprocably supporting the shift ring or flow-control member M of the pump, bearing plates I5 being inserted between the mating portions of the bosses I2 and the shift ring [4. Rotatable within the shift ring l4 of the pump is a secondary ring it which' provides a track wa for the outer end portions or heads 11 of a plurality of radially disposed pistons I8. The pistons l3 are'reciprocable in radially arranged bores l9 as herein outlined, form no part of the present invention and may consist of one of a number of different types or constructions of pumps, with the exception of the shift ring 14 or an equivalent shiftable flow-control member.

The shift ring [4 is provided upon its outer .surface with a pair of diametrically opposed flat bosses 21 which lie in abutting engagement with the .outer ends with a pair of diametrically opposed piston heads or plungers 28 which are slidably mounted within bores 29 formed in thesides 10f. the outer casing of the pump. The outer casing H is formed with flat side regions 30, to

It will be understood, that the details of construction of the pump mechanism,

which are attached, asby bolts 3|, thecooper- I iatively flat faces of a pair of inner piston housings'32." The housings 32 .are formed with centrally disposedbores 33 which provide continuations of the bores 29, and slidably support the enlarged end portionsof the plungers 28. Towardtheir outer ends, the piston housings 32 are formed with relatively enlarged bores 34- in which are :slidably mounted a pair of annular piston members 35 which are, in turn, slidably carried upon the reduced shank portions 36 of the plungers 28. At their .extremeouterends, thehousings 32 are provided with another and still enlarged set of bores 31,.which terminate at the flat outer ends of the housings 32 andcom- -inunicat'e with the second bores 34. The housings 32 are further formed with fluid inlet openlugs 38 which communicate with passages 39 leading to the enlargedouter end bores 31of. the

housings. Positioned. within the inlet openings .38 of the innerhousings 32 are fluid conduits 43 and-4|- tailed in a direction toward the reservoir.

tively greater diameter than the bores 31, whereby the outer end portions of the inner housings 32 provide annular shoulders 44 at one end of the bores 43. The outer ends of the bores 43 communicate with relatively reduced recesses 45, whose reduction in diameter provides a second set of shoulders, 46 at the. outer ends of the bores 43. .1 I

Slidably mounted within the bores 43 for wiping engagement with the walls thereof are a pair of annular blocks or pistons 41, each of which is provided with an axial opening 48 through which extend a pair of fluid-pressureresponsive piston plugs 49, the outer ends of which are slidably mounted within bores 53 formed in the outer end housings 42, with the inner ends of the plugs 49 being maintained in abutting engagement with the reduced end pcr tions of the plungers 23. The reduced bores 50 of the outer housings 42 terminate in relatively enlarged fluid inlet ports 5| which receive the ends of a pair of fluid supply conduits 52. The

outer end housings 42 are further provided with fluid-conductingpassages 53 which communicate respectively with the recesses 45 and a pair of fluid inlet ports 54 for the reception of fluid conduits 55 and 56. Extending through the outer ends of the plugs 49 and communicating'with the recesses 45, are a pair of restricted T-shaped relief passages 5'! which prevent hunting movement of the plugs upon. application of relatively extreme pressures thereto. As with the connection. between the outer casing If and the inner housings 32, the outer end housings 43 are connected with the inner end housings 32 by means of screw threaded bolts 58, and liquidtight engagement between the two housings is aided by an annular packing ring 59. disposed within an annular recess formed upon the inner faces of the outer housings 42.

, Connected with the fluid inlet and outlet 25 and 26 of the pump Ill are a pair of fluid-conducting manifolds 60 which communicate at one of their ends with a liquid reservoir BI, and at their opposite, ends with-the respective ends of a hydraulic, press cylinder 62. In the usual manner, a piston 63is mounted for sliding movement withinthe cylinder 52 for wiping engagement with the inner wallsthereof. The piston is pro vided with; an axially disposed piston rod or plunger 34 which extends vexteriorly of the cylinder 62 to join a press-operated member, such as vonelplaten of a press, not shown Interposed withinvthe conduits 60, between the reservoir 3i and the pump I0, are check valves 35 by means'of which fluid flow may normally be our- Also interposed between each of the conduits 60 and thereservoir 6| are a pair. of safety valves 68 which function to automatically return fluid 10.1 It will be understood, that the immediately preceding description of the pump hydraulic circuit is common to the ordinary press-actuating hydraulic circuit, and. in its specific aspects, forms no part of the present invention. ,1-

Thexpump 10 operates,. depending upon the positionof .the shiftsring 14, to displace fluid through eitherof the conduits .60 at varying pressure levels ranging from zero delivery to full delivery.., When the shiftring l4 occupies a posiact. upon the unseated right-hand piston ring 35 and the faces of the. reduced shank portions 96 of the plungers Z6, anddue to the larger effec-- tive pressurearea within the right-hand housing, provided. bothby the piston ring 35 and the plungerZB, the, right-hand plungerlii and piston-ring35 will move in opposition to the opposite plunger tomove the shift ring once again to its neutral position.,, Referring .to Figs..2 and 3, it will be seen that theextent of outward movement of either of the plungers 28 is determined by the positions of the relatively larger annular pistons 4?. Normally, to permit theshift ring I4 to move toitsfull displacement position, the .valves 19 and H are conditioned to permit fluid to-freely exhaust through the conduits 55and 56 whereby the-pistons 4! may be pushed outwardlyinto engagement with the shoulders 49 upon outward movement of either of the plungers 28. To hold the shift ring it against movement tinto a full displacement. position in either direction-fluid underpressure may beintroduced alternately orsimultaneously through either of the conduits 55 or 56 to react'upon the outer .faces of thepistons4lto hold the same in in; intermediate positions between neutral and Theseintermediate positions are extremelyadvantageous when the full displacement positions.

associated pump-actuated mechanism takes the form of a hydraulic press orthe llikfi, in that. the

advancing stroke of the piston-93 and its .associated plunger 54 may be reducedin' speed, by

decreasing thedelivery level of the associated pump Where slow speeds are desirable, either of the valves ill or ll may be actuated to pressurize-the chamber within the outer-end housings 42. adjacentthe pistons 4? to limit the outward movement of the adjacent plunger 28.' At

anytime when increased speeds are required or desired,'the pressure acting upon the pistons 4'5 may be relieved by'conditioning the valves Hi and H, so as to allow fluid within the outer-end housings 42 to exhaust or return to the reservoir, atwhich time the plungers 28 are free to move the shift ring to either of its extreme full delivery positions.

Acting in opposition tothe movement of the plungers 28 are the relatively small diameter plugs" 49'. which are pressurized by fluid within the main pump circuit. It will be understood,

that the pressures within the mainpump circuit are of a substantially increased value relative to the pressures afforded by the pilot pump circuit. -Accordingly, due to the relatively reduced effective pressure areas of the plugs to in relation the pressurearea-s of the plungers '28, the pilot pressure acting upon the pressure areas of the .pistons 28 and 35 ispredetermined so'as to normally overcome the pressure exerted by the plugs 49. to freelymove the shift ring It to its various fluid-displacement positions. .tively extreme back pressures are built up within However, as relathe delivery of the pump It, such as will occur when the piston 63 reaches the. ends of its compression or return strokes, the-diameter of the j plugs 49 Bee computed in relationto a predete min ck s r tha thexs en e onerable to exert sufiicient forcerupon either oi the plungers 28 in opposition'to the opposite plunger .to, return the. shift ring to a neutral position, at which time theback pressures are'reduced by the consequent reduction in pump pressure. Thus,- an automatic return of the pump to a neutral position is afforded when back pressures of a predetermined magnitude are established at the delivery side of the pump.-. It should here be noted, that should leakage occur within thedelivery side of the pump circuit the pressure acting upon either of the plug 49 will be decreased to once again permit the pilot pump-actuated plungers to come into play and shift the ring into a position causing displacement of fluid, by the pump. In this manner, a balance between the pilot pump system and the main pump sysjtem is effected whereby substantially constant pressures will bemaintained at the delivery side of the pump, regardless of leakage or slippage within such delivery side. Fig. 5 of the drawings discloses in simplediagrammatic form a unidirectional variable delivery, fluid pump, generally indicated by the numeral 95, havinga shiftable flow-control, member 86 movable between a neutral no-delivery position-and a single full-deliveryposition. Arranged. on opposite sides of the pump, area pair of piston housings, 81 and 88.v The lefthand housing 8? is formed with an internalbore 89 of relatively large diameter in which is slidably mounted a reciprocable pressure-responsive piston 90 having a piston rod or plunger 9! extending through the pump casing for abutting engagement with one side of the flow-control member 86. Communicating with the bore 89 of the housing'il'l is a, fluid inlet conduit 92 which is directly connected with the delivery of a relatively lows-pressure pilot pump. 93, the latterbeing provided with a fluid supply line 94 extending within a fluid reservoir 95. Interconnecting the fluid inlet conduit 92 and the supply line 94, is "a pressure relief circuit including a pressure reliefvalve 96 whichfunctions in the usual manner in response to a predetermined maximum pressure within the delivery of the pump .99 to by-pass fluid from the inlet conduit 92 Jtothe supply conduit 94 for recirculation by vthepump. From this assembly, it will be seen thatthe piston 99 is constantly subjected to a predetermined pump pressure tending to force the flow-control member 86 to its full-delivery position.

The opposite housing 88 isformed with a relatively reduced diameter 'bore 97 in which is mounted a small diameter piston 98 which extends through the pump casing for engagement with the; opposite side of the flow-control member of the pump '85. Thebore 9! is connected by way of a fiuid inlet conduit-99 with the delivery line I00 of the pump 85, on the pump side of; a fluid-actuated motor llll. Thus, the piston 98 is at all .timessubjected to the pressure withvin thedelivery line I 09.

' From this relation of elements it will be seen that by. proper determination of the relative eii ective pressure areas of thepistons 90}and 98,

. thefluid delivery of the pump 85 will at all times maintain a substantiallyconstant predetermined pressure. upon the, motor llll, as thepiston .98 willbe effectivetoshift the flow-control mem- ,.ber.; of the pumpjoward its .no-Qde1ivery. position in opposition to the pilot pump-responsive piston .90 -and in response to a 'predetermined'maximum pressure withinthe'delivery ofthepump 85. 1 In; ViBWfOf the "foregoing, it willibeseen that said plungers and responsive under influence of fluid aerate paratus-jot controlling thefluid delivery oi vari nn-accordance with, this invention 1 o:

tion ofzvar eb d ive y. pumps ViQIISI-YQRIIQWII control systems.- Controls; f

their function of providing positive means to automatically control the maximum pressure A ve y u s, on o han ms form vid unc it ca m e c ntr l: v the per:

rwhich has-he toiorebeens-impossible or impractical with p present; invention are further characterize alternate the speed of delivery of an associated pump, and through the provision of means to output of the pump and to maintain such maximum pressure output regardless of leakage or slippage within the mechanism operated by such pump.

While present preferred embodiments of the invention have been disclosed'in detail it will be manifest that various modifications as to structural details are possible without departing from the spirit of the invention or the scope of the following claims.

I claim: i

1. A control device for a variable delivery fluid pump having a flow-control member shiftable between opposite full delivery positions and a neutral no-delivery position, comprising a plurality of opposed fluid-actuated plun ers arranged on opposite sides of the flow-control mem: ber of said pump and operable individually to shift the flow-control member to either of its full-delivery positions and operable in unison to shift the'flow-control member to its neutral position, fluid pressure-responsive stop devices engageable with said plungers for limiting the shifting movement of the flow control member of said pump, said stop devices being operable in opposition to the influence of said plungers to limit the shifting movement of the flow-control member to intermediate positions between its neutral and full-delivery positions, and oppositely disposed piston means engageable with to a predetermined delivery pressure of said pump for shifting the flow-control member of said pump from a fluiddelivery position toward a no=delivery position in opposition to the influence of said plungers.

2. A control mechanism for a variable delivery fluid pump having a flow control member shiftable between two full-delivery positions and an intermediate no-delivery position, comprising a plurality of opposed servomotor casings arranged on opposite sides of the pump and provided with a plurality ofinternal pressure chambers each having fluid inlets, a plurality of opposed fluid pressure-responsive plungers slidably mounted in one set of said chambers and engageable with the flow-control member of the pump on opposite sides thereof, valve means to selectively direct pressure fluid simultaneously to each of [the chambers containing said plungers or separately to each of the chambers while connecting the op posite chambers to exhaust, a plurality of relatively increased area fluid-pressure-responsive stop devices mounted for limited reciprocating movement in another set of said chamber adsaid stop devices being opjacent said plungers, erable in response to fluid pressure acting thereon to'limit the sliding movement of said plungers pressure, and a plurality tively operable to 7 thereof for shifting 'thesaine" saidipl ungers in oppositiontozfl ingtherepnein a-:.direction5.to;ish trolmember; of thepumpxto 1t 3, lnra icembin tion fluid-pump havin a. pres ur n lam mb. H Maid-cr mb -S opposite full delivery positi A x ate me al-ver restless/ control device prising a pair of opposed, relatively low pressure, fluid-actuatedlplungprsgengage ble with the flow en ral, membemivsaid pumn 0n op gs e side delivery'positions or to its no-delivei y p t1o a pair of relatively low pressure, fluid-actuated stop members engageable with said plungers for limiting the shifting movement of the flow control member of said pump to hold the same against the action of either ofsaid plungers in intermediate positions between no-delivery and full delivery positions, said stop members having increased effective pressure areasin-relation, to said plungers; fluid pressure-supplying means connected to supply pressure fluid to said pair of plungers and to said pair of stop members, said last named means including, valve means selec.

direct pressure fluid simultaneously to both of said pair of plungers, oralternately, to one or the otherof said pair, of plungers and toselectively direct fluid pressure to said pair of stop members; and a pair of op-; posed pump pressure-operated pistons engage-' able with said plunger'sfor shifting the flow control member of said pump from its full delivery positions toward its no-delivery position against the action of either of said plungers and in response to a predetermined delivery pressure of said pump, said pistons having decreased effective pressure areas in relation to said plungers.

4. In combination with a variable delivery fluid pump having a pressure outlet and a flow-controlling member carried in said pump and movable between a neutral position providing for no circulation of fluid through the pressure outlet of the pump and a full delivery position providing for maximum displacement of fluid through the outlet of the pump; a control device comprising a pair of cylinder-forming casings positioned on'opposite sidesof said pump; a first set of fluid-pressure-responsive plungers carried in the respective casings and engageable with said flow-controlling member for shifting the latter between neutral and full delivery positions; a sec ond set of fluid-pressure-responsive stop members positioned in the respective'casings and engageable with said first set of plungers, said second set of stop members being operable, when simultaneously subjected to fluid pressures, to maintain set of plungers and said second set of stop memof reciprocable pistons slidable within said casbers and operable, in response to fluid pressure. to limit movement of said flrst set of plungers in shifting said flow-controlling member from its neutral position toward its full delivery position; a a pilot pump circuit connected to supply pressure fluid respectively to said first set of plungers and i said second and third sets of stop members, said circuit including valve means operable to direct 1 pressure fluid either simultaneously or selectively to said first set of plungers, said second set of stop members, and said third set of stop members; and

fiuid -pressure-responsive means in said-Casings;

engageable with said first set of plungers and communicating with the pressure outlet of the pump for shifting said flow-controlling member towardits neutral position in opposition to forces exerted thereon by said first set of plungers in response to a, given high pressure within the pressure outlet of said pump.

i I -WARREN R. TUCKER.

REFERENCES CITED The following references are of record in the file of this patent:

Number 12 UNITED STATES PATENTS Name Date Ernst Apr. 21, 1936 Douglas Jan. 3, 1939 Wiedmann Nov. 7, 1939 Ernst Jan. 28, 1941 Kendrick Dec. 15, 1942 Muller Jan. 1, 1946 Waldie Apr. 8, 1947 

